Reye Syndrome Surveillance -- United States, 1989

Reye syndrome (RS) is an acute illness that occurs almost
exclusively in children; it is characterized clinically by profuse
vomiting and neurologic dysfunction, sometimes progressing to
delirium,
coma, and death.* Continuous national surveillance for RS was
established in December 1976 (1). This report summarizes RS cases
for
the 1989 surveillance year (December 1, 1988-November 20, 1989).

For the 1989 surveillance year--a period characterized by
widespread influenza B activity--25 cases of RS were reported by
state
health departments to CDC's National Reye Syndrome Surveillance
System
(NRSSS). This equals the lowest number of cases reported since
continuous national surveillance began and is 25% of the lowest
number
previously reported during a year with extensive influenza B
activity
(Table 1).

Nineteen (76%) of the patients had a reported antecedent
illness
within 3 weeks before onset of vomiting or neurologic symptoms; 13
had
respiratory illnesses; three had varicella, and three had diarrhea
without respiratory symptoms. Eighteen (72%) cases occurred in
January,
February, and March--the peak months for respiratory viral
infections,
including influenza types B and A(H1N1).

Of the 25 reported RS patients, 14 (56%) were female; 23 (92%)
were
white, one was black, and for one, race was unknown. Nineteen
patients
were greater than or equal to 5 years of age, and six were less
than 5
years of age, representing declines of 72% and 82%, respectively,
since
1986, the most recent prior year in which influenza B was the
predominant influenza strain.

Approximately 70% of patients were admitted to hospitals in
precomatose stages of RS (stages 0, 1, or 2). The largest number
(seven) of patients were identified with stage 2 on admission,
followed
by stage 1 (six) and stages 0, 3, 4, and 5 (three each). The most
severe phases of illness after hospitalization were stage 1 (two),
stage 2 (seven), stage 3 (two), stage 4 (three), and stage 5 (six).
One
patient received treatment that precluded classification (i.e., she
had
received anesthetic or paralyzing agents in her treatment); the
most
severe stage was not reported for four.

Of the 24 patients for whom short-term outcomes were reported,
10
died (case-fatality rate: 42%).
Reported by: Local and state health departments. Epidemiology
Activity,
Div of Viral and Rickettsial Diseases, Center for Infectious
Diseases,
CDC.

Editorial Note

Editorial Note: The annual number of cases reported to the NRSSS
has
decreased sharply since 1980 (Table 1), coinciding with increased
public awareness of the association between the ingestion of
aspirin
during antecedent varicella or influenza-like illness and
subsequent
development of RS (2-7). In addition, the use of aspirin-containing
medication to treat children with these viral illnesses has
decreased
(1,8,9).

The total number of reported RS cases in 1989 is lower than
would
be expected in a year with substantial influenza B activity. Before
recognition of the association between aspirin use and risk for RS,
periods of increased influenza B activity were characterized by
substantial increases in the number of RS cases (10). In 1989, the
number of reported cases was the same as in 1988; however, when
compared with 1986, the last year with predominant influenza B
activity, RS cases markedly decreased.

For 1985, 1986, and 1987, the percentage of patients less than
5
years of age were 53%, 38%, and 53%, respectively. These
percentages
were higher than in past years (1978-1984) and raised concerns
that, as
the overall number of reported cases decreased, a greater
proportion
would occur in the less than 5-year age group--a group for whom the
diagnosis of RS may be complicated by metabolic disorders with
manifestations similar to RS (11,12). For 1988 and 1989, the
percentage
of cases reported in this age group decreased to previous levels,
suggesting that physicians may be more likely to rule out these
metabolic disorders before diagnosing RS.

Preliminary results from 1990 surveillance indicate a
continuing
decline in the number of RS cases in the United States. As RS
becomes
increasingly rare, interest in reporting may also wane. Health-care
personnel and public health agencies are urged to continue
reporting to
the NRSSS to assure adequate monitoring of the changing
epidemiology of
this illness.

References

Barrett MJ, Hurwitz ES, Schonberger LB, Rogers MF. Changing

epidemiology of Reye syndrome in the United States. Pediatrics
1986;77:598-602.

*According to CDC's case definition, the following conditions must
be
met for consideration as a RS case: 1) acute, noninflammatory
encephalopathy documented a) by alteration in the level of
consciousness and, if available, a record of cerebrospinal fluid
containing less than or equal to 8 leukocytes per mm3 or b) by
histologic specimen demonstrating cerebral edema without
perivascular
or meningeal inflammation; 2) hepatopathy documented either by a
liver
biopsy or autopsy considered to be diagnostic of RS or by a
threefold
or greater rise in the levels of either serum aspartate
aminotransferase, serum alanine aminotransferase, or serum ammonia;
and
3) no more reasonable explanation for the cerebral and hepatic
abnormalities.

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